The present invention relates to hydrocarbon-soluble amines and amine derivatives of high molecular weight carboxylic acids as an additive for hydrocarbon compositions such as gasoline, fuel oil and lubricating oils including greases, industrial oils, gear oils and lubricants for engines and other equipment having moving parts operating under boundary lubricating conditions so as to improve the antifriction property of said composition.
There are many instances, as is well known, particularly under "Boundary Lubrication" conditions where two rubbing surfaces must be lubricated, or otherwise protected, so so to prevent wear and to insure continued movement. Moreover, where, as in most cases, friction between the two surfaces will increase the power required to effect movement and where the movement is an integral part of an energy conversion system, it is most desirable to effect the lubrication in a manner which will minimize this friction. As is also well known, both wear and friction can be reduced, with various degrees of success, through the addition of a suitable additive or combination thereof, to a natural or synthetic lubricant. Similarly, continued movement can be insured, again with varying degrees of success, through the addition of one or more appropriate additives.
Additives reduce friction between lubricated, moving, metal parts have the propensity to improve fuel economy in the gasoline engine. The mechanism by which this is achieved is conjectured to be by reduction of friction attendant to said moving parts as between, for example, the piston rings and cylinder wall in the engine. If friction can be reduced in the engine, more energy, provided by the fuel, is available to do useful work. In order for an additive to function, it must be delivered to the friction-inducing surfaces efficiently. This can be achieved by incorporating a friction-reducing additive in the lubricant or in the fuel.
Although many classes of compounds work as friction-reducing additives, it is possible to categorize them as either ashless and metal containing. The predominant additives in the metal-containing class are compounds of molybdenum. In the ashless category, many different chemical classes are disclosed such as is taught in U.S. Pat. No. 4,105,571 which although particularly directed to lubricating compositions containing an ester of a polycarboxylic acid with a glycol (the antifriction additive) reports of other ashless additives (see column 1, lines 57 to col. 2, line 8 wherein it is stated "Additive mixtures . . . valve lifter wear . . ." The key features of these materials is oil solubility, minimum interaction with other components of the lubricant formulation, efficiency of action and minimum contribution to the total cost of the oil.
Hydrocarbon-soluble carboxylic acids such as the above-referenced dimer acids are thus well known as are the amines or amine derivatives thereof (see the monograph "The Dimer Acids" edited by E. C. Leonard and published by Humko Sheffield [1975] of Memphis, Tenn. and U.S. Pat. Nos. 2,526,044, 3,223,631 and 3,010,782.
In light of the foregoing, the need for improved lubricating compositions that will permit operation of moving parts under boundary conditions with reduced friction is believed to be readily apparent. Similarly, the need for such a composition that can include conventional base oils and other conventional additives and can be used without the loss of other desirable lubricant properties, particularly those provided by zinc dialkyl dithiophosphates, is also readily apparent.